1. Field of the Invention
This invention constitutes the addition of a blue dye or other blueing agent to aqueous ophthalmic solutions, generally available, to give the apparent effect of increased whiteness to the eyes.
Vasoconstrictors such as naphazoline hydrochloride and tetrahydrozoline hydrochloride are currently being used to relieve redness of the eye and have been in use for sometime. The effectiveness of ophthalmic solutions containing these vasoconstrictors, however, are dramatically improved in their ability to increase the whiteness of the sclera when blueing agents are added thereto. Moreover, current ophthalmic solutions which do not contain any vasoconstrictors whatsoever also become effective in increasing the whiteness of the eye when combined with the instant invention.
2. Description of the Related Art
Substantially all whiteness formulas used at present assess a white color sample as all the whiter, the lighter and bluer it actually is. See, E. Ganz, "Whiteness Formulas: A Selection," Applied Optics, vol. 18, No. 7, at page 1073 (1979). For instance, it is a common practice to use a blue dye as a whitening agent in detergents due to a mechanism in which a yellow cast in the fabrics is covered by the blue dye. See, Example 1, Cahn and Lynn, Jr., "Encyclopedia of Chemical Technology," Third Ed., Vol. 22, John Wiley & Sons, Inc., New York, N.Y., 1983, at page 399.! Similarly, the same mechanism (addition of blue dyes or pigments) is being used in the plastic industry to mask the yellowing of the plastics upon exposure to gamma-ray sterilization.
The present invention is based on applying this mechanism to the eye. Application of eye drops to the eyeball causes the lower well of the bottom eyelid to fill with the aqueous solution. The normal process of blinking causes the top eyelid to pull the solution from the lower well up and across the surface of the entire eyeball as it opens, increasing the apparent whiteness of the sclera portion of the eye.